How do you find the effective radius of a tire?

C = 2 * pi * r. Solve for r. r = C / (2 * pi). And from there having the section dimensions of the tire we can calculate the effective radius, which is the distance from a circle section A to its center.

How do you calculate tire rolling resistance?

Example 18-20. Note 1: Rolling Resistance Coefficient μR is defined by μR = F/G, where F is the force necessary to pull the axle of a tire horizontally in the direction of travel, and G is the vertical load on the tire which is assumed to roll on a flat horizontal surface.

What is the radius on a tire?

The rim width is the distance between the outer & inner rim flanges on which the tire beads seat. The free radius is the distance from the wheel axle centerline to the outer tread surface of the unloaded, properly inflated tire.

Does tire pressure affect diameter?

So…. a 2 psi change in tire pressure (above 26 psi) results in a 1/32″ change in radius… and therefore a 2/32″ change in diameter. 3.14 X 2/32″ (pi x d) = a little over 3/16″ change in circumference. Double that for pressures between 26 psi and 20 psi.

What is the running resistance of the vehicle?

The running resistance is the sum of rolling and aerodynamic resistance. Running resistance is directly proportional to the mass of the vehicle. As the mass of vehicle increases rolling resistance increases and thus, the running resistance increases. The aerodynamic resistance is independent of the vehicle mass.

How do you find the radius of a static load?

SLR Static Loaded Radius is the radius from the wheel centre down to the ground, at reference load and pressure. The difference between unloaded radius and static loaded radius is called deflection. This value varies between 15-30% of the tire section height, depending on tire type.

How do I know my wheel size?

First, start with the wheel size for your vehicle. You can find that on the sidewall of the tires on your original wheels or the inside frame of the driver’s door. Check out Tire Size Explained (Reading the Sidewall) for more. The wheel diameter (in inches or millimeters) is the fifth set of numbers and letters.

How big of an air compressor do I need to run a tire machine?

A CFM of 20-25 for a small to medium-sized shop should be adequate. Keep in mind, once you pick a compressor, you will also need fittings, a filter to put on the outlet coupler, hose(s), and Teflon tape.

How is the radius of a tire determined?

A free rolling tire generally travels farther in one revolution than determined by its center height, H, but less than determined by the free tire radius. In this example the free radius is 316.2 mm and the vertical deflection is approximately 20.0 mm, so H= H = 296.2 mm.

How does tire deflection affect the rolling radius?

In general, the effective rolling radius changes with tire deflection ρ. We may write FIGURE 8.11. The rolling wheel subjected to longitudinal slip (slip speed Vsx ). with rf denoting the free (undeformed) radius that may vary along the tire circumference due to tire nonuniformity.

Where do I find the effective rolling radius?

In Chapter 8 the notion of the effective rolling radius has been introduced. Figure 8.12 shows the results of experiments of tires running over a drum surface. In Subsection 8.3.1 the theory is restricted to a linearized representation of the variation of the effective rolling radius with radial defection.

How is the theory of rolling radius restricted?

In Subsection 8.3.1 the theory is restricted to a linearized representation of the variation of the effective rolling radius with radial defection. The complete nonlinear variation versus normal load FN may be described by the expression:

How do you find the effective radius of a tire?